As psychologist and consumer researcher Alice Isen of Cornell University has shown, finding a nickel in a public telephone can put you in a good mood.5 This idea has been employed by upscale hair salons, which serve beverages; at airline check-in counters, where you can get candies; and at restaurants serving an amuse-gueule.

We note that many criticisms have been made of the original studies, and that attempts to replicate them have not succeeded (Marshall and Zimbardo 1979; Maslach 1979), and that hundreds of studies have shown the role of affect (for a review work see Isen 1984).